Railyard remote control systems for locomotives (hereinafter referred to as Remote Control or RC systems or simply RC) are known in the railroad industry. Remotely controlled locomotives are controlled through use of a radio transmitter and receiver system operated by an operator not physically located at the controls within the confines of the locomotive cab. One such system is commercially available from Canac Inc. and is described in Canac's U.S. Pat. Nos. 5,511,749 and 5,685,507. Another RC system is offered by Cattron-Theimeg, Inc.
It is also known to provide distributed power control systems for locomotives (hereinafter Distributed Power or DP systems or simply DP), in which the operation of one or more remote locomotives (or group of locomotives forming a train consist) is remotely controlled from the lead locomotive of the train by way of a radio or hard-wired communication system. One such radio based DP system is commercially available under the trade designation Locotrol® radio, and is described in U.S. Pat. No. 4,582,280, which enables communications among locomotives when connected together to form a consist or at spaced locations along the length of train when the locomotives are spaced apart by one or more railcars for so-called “inter-consist” communications. Hard-wired systems have been available for over 20 years from companies, but provide communications between locomotives only when they are directly connected mechanically together to form a consist and electrically together via so-called Multiple Unit (MU) cables for so-called “intra-consist” communications.
DP control is provided using an FCC-approved frequency allocated for railroad operations in the 450 MHz frequency range at power levels of about 30 Watt. DP radio systems are capable of providing reliable and accurate locomotive control during conditions when the radio channel is free of interference. However, when interference is present, special communication techniques, such as unique locomotive identifiers and time randomization, have been developed to mitigate communication conflicts, such as in situations where a large number of locomotives are operated within a relatively small geographical area, such as in a train yard, industrial site, etc.
Known RC radios have adopted the same FCC-approved frequency, which adds to communication conflicts in high-volume train yards. In addition, because RC locomotives are generally operable in a rail yard while DP locomotives are relatively transient, RC radios add to the EM noise around the train yard for neighboring residents and further restrict the available bandwidth for other communications on the FCC-approved frequency.
It is also known to communicate between individual cars in a train via radio to control braking and other functions for what is commonly referred to in the industry as Electronically Controlled Braking, (ECPB). See for example, U.S. Pat. No. 6,400,281 in connection with an innovative technique of train communication for providing ECPB.
In another regard, recently in the U.S., the Federal Railroad Administration (FRA) has proposed regulations that prescribe that the status of certain locomotive systems, such as the dynamic braking system, in trail locomotives be communicated to the operator in the lead locomotive. Typically, the Multiple Unit (MU) cable is provided between adjacent locomotives for conveying intra-consist data. Unfortunately, the existing analog communication protocol of the MU cable lacks the communication capacity to meet these regulations. In addition, when the locomotives are arranged in a set of distributed consists at spaced locations along the train there is no effective way to communicate the MU cable intra-consist data of each consist to the lead locomotive via DP radio in that these are separate systems that typically do not communicate with each other.
The types of radio systems described above, e.g., RC, DP, MU, and ECPB, each may have widely varying communications needs to provide a respective train functionality yet each of such system may be competing for the same limited radio bandwidth. Thus, it would be desirable to provide communication system and techniques that appropriately address any desired train functionality notwithstanding of a limited frequency spectrum.